Room Full of Mirrors: A Biography of Jimi Hendrix by Charles R Cross 384pp, Sceptre, £18.99

It is not often that a pop biography, written 35 years after the event, succeeds in dismantling the fables and revealing the reality of a performer's life with quite such clear-eyed acuity as Room Full of Mirrors. When Jimi Hendrix first arrived in London in September 1966, it was as if some exotic guitar god had descended, fully-formed. The terse sleeve notes on his debut album, Are You Experienced, released eight months later, famously hinted at an impossibly romantic provenance. "Left school early and joined the Army-Airborne, but was invalided out with a broken ankle and an injured back. Started hitching around the Southern States, guitar pickin'. One night one of the Isley Brothers heard him playing and offered him a place in their band ..."

The truth, as Hendrix might have put it himself, goes a little deeper than that, and Charles R Cross has got as close to it as anyone yet, in his exhaustive and groundbreaking account of the life of the greatest guitarist in the history of rock. In the case of Hendrix's early departure from the ranks of the 101st Airborne division of the US Army, the real story turns out to be almost comically divergent from the myth. On Hendrix's medical examination records of May 1962, the army doctor, Captain John Halbert, noted a string of chronic health "complaints" including "masturbating; dizziness; pain ... in the left chest ... trouble sleeping; personal problems" and recommended that Hendrix should be discharged because of his "homosexual tendencies". This highly unlikely gambit enabled Hendrix to extricate himself from the forces less than a year into his three-year enlistment period without facing a prison term.

The story of Hendrix's childhood is less amusing, and while previous biographies have made general allusions to his difficult upbringing, Cross spells out the painful details of grinding poverty, emotional neglect and personal tragedy that explain much about Henrdix's flamboyant yet deeply troubled nature. Born in Seattle in 1942, when his mother, Lucille, was 17 years old, Hendrix was shunted from pillar to post all his young life. He was three when he first met his father, Al Hendrix, on the day he came to California to reclaim his son from the family that had been caring for him up to that point. Al gave Jimi his first disciplinary spanking on the long train ride back to Seattle.

Al and Lucille, who were both heavy drinkers, went on to have five more children, four of whom were severely disabled. After divorcing Al, Lucille died when Hendrix was 15. Small wonder that, once the unusually sensitive boy had discovered a talent for playing the guitar, he should take refuge in music. This, in itself, became a bone of contention, and Hendrix dared not leave his guitar unattended in the family home for fear of it being destroyed by Al, who believed his son's interest in the instrument to be unhealthy.

Cross, who lives in Seattle, is best known for his highly acclaimed biography of Kurt Cobain, Heavier Than Heaven. His local knowledge gives him an edge over other biographers when it comes to exploring Hendrix's early years, as does his impressive rate of tracking down and talking to those involved with him at the time, a process involving "more than 325 interviews over the course of four years".

The story falls more closely into step with previous biographies once Hendrix arrives in London and his accelerated ascent to global stardom begins. One voice that is missing from the 325 interviews is that of Mitch Mitchell, who played drums with Hendrix virtually from the day he stepped off the plane, until the week of his death in London four years later in September 1970. And while Cross is punctilious in referencing the events of Hendrix's life during this tumultuous period, he tends to skate rather airily over the musical details. Even so, he draws interesting links between several of Hendrix's gentler songs - such as "Angel" and "Castles Made Of Sand" - and his feelings of sadness over the loss of his mother. And having read this book you will never again stop to wonder from whence came the anger and despair voiced in songs such as "Manic Depression" and "I Don't Live Today".

Cross has no time for conspiracy theories, and dismisses the bizarre claims of the late Monika Danneman over the circumstances surrounding Hendrix's death. Nor does he sign up for some of the more fanciful interpretations that have been ascribed in the past to Hendrix's beliefs and behaviour patterns. Cross maintains that, as an ex-soldier, Hendrix was a supporter of the Vietnam war, at least in the early days. If he had intended his famous, feedback-drenched version of the American national anthem to be a political or anti-Vietnam statement he never spoke of it. "We're all Americans," he said at a press conference. "It was like 'Go America!' ... We play it the way the air is in America today. The air is slightly static, see."

While Hendrix quickly became one of the most celebrated musicians of all time, a figure on a par with his own hero Bob Dylan, the picture that emerges from behind the scenes is of a man drifting rudderless in a sea of lifelong insecurity, heroically unable to commit himself to anything beyond the pleasures and concerns of the moment. By the closing chapters, as he stumbles from abandoned gig to trashed hotel room, either beating up groupies or begging them to marry him, Hendrix has turned into the Pete Doherty of his day.

Cross is sparing in his analysis but always to the point. Recounting an interview Hendrix gave to a Danish journalist just weeks before his death, in which the troubled guitarist insisted that other than his music he felt he had nothing to live for, Cross reflects momentarily on the likely significance of this dramatic statement. "Jimi was stoned out of his mind at the time but there was truth in the confession - the life he had created as a star was as lonely and as isolating as his fractured childhood."

· David Sinclair's Wannabe: How The Spice Girls Reinvented Pop Fame is published by Omnibus. To order Room Full of Mirrors for £17.99 with free UK p&p call Guardian book service on 0870 836 0875.